21243357 has 16 divisors (see below), whose sum is σ = 31706880. Its totient is φ = 14056416.

The previous prime is 21243347. The next prime is 21243359. The reversal of 21243357 is 75334212.

It is not a de Polignac number, because 21243357 - 2⁶ = 21243293 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 21243357.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21243359) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 828 + ... + 6570.

It is an arithmetic number, because the mean of its divisors is an integer number (1981680).

Almost surely, 2^21243357 is an apocalyptic number.

21243357 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21243357 is a deficient number, since it is larger than the sum of its proper divisors (10463523).

21243357 is a wasteful number, since it uses less digits than its factorization.

21243357 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5889 (or 5883 counting only the distinct ones).

The product of its digits is 5040, while the sum is 27.

The square root of 21243357 is about 4609.0516378101. The cubic root of 21243357 is about 276.9540471239.

Adding to 21243357 its reverse (75334212), we get a palindrome (96577569).

The spelling of 21243357 in words is "twenty-one million, two hundred forty-three thousand, three hundred fifty-seven".